In general terms, two types of subsidiary bodies are created to advise the Parties to MEAs. The first type is open to representatives from all Parties, and the second is a small expert group. Smaller bodies are usually established to provide specific technical advice to MEAs. Some notable examples include the scientific and technical advisory bodies to CITES, PIC, Ramsar, and Ozone Conventions. In such cases where only a limited number of experts are invited to participate, criteria for invitations usually include strict stipulations for regional representation. ( Source: http://www.un.org/earthwatch/about/docs/sciadv2p1.htm)